"How many drugs did you lot seize in the run up to Glastonbury or we only doing tweets like this for black events?" grime artist Stormzy asked.

Those on the ground at the carnival say the atmosphere is "positive".

"After carnival you hear about all these madnesses, but we've never experienced or seen it because we don't have that sort of atmosphere," says Errol Smith, from King SSP Sound System - one of more than 30 that play at the carnival.

"It's peaceful - everyone jumping up and down and having fun. We've never had any issues or problems in the eight years we've been there. From where I've been, people are just enjoying themselves."

Carnival has experienced trouble over the years including a riot in 1976 and five deaths between 1987 and 2004.

At last year's event, police made 454 arrests - the highest for 10 years - with 90 being for possession of an offensive weapon, 17 for assault and 169 for drugs.

Two people suffered serious injuries after being stabbed.

The Metropolitan Police Federation has said its rank-and-file officers "dread" working at the carnival.

Speaking after last year's event, federation chairman Ken Marsh said the carnival was being "hijacked" by troublemakers intent on "turning it into a bank holiday battleground".

"Last year we had an officer stabbed. This year colleagues were assaulted, abused and spat at," he said. "Forty-three were injured - with eight needing hospital treatment. How can that be right? It's completely and utterly unacceptable."

George Ruddock, editor and managing director of black newspaper The Voice, says there is a "stigma" attached to the carnival.

"It's targeted because it's got its origin as being a black cultural event," he said.

"Fifty-one years later the police still think it's predominantly black people who will be there but surprise, surprise, it won't be. There will be a mixture of cultures there.

"I think if there's any kind of event which has predominantly black entertainment and attracts a crowd, there would still be this kind of focus."

Ben Wilson from the London School of Samba, which has been performing at the carnival for 34 years, says the stories which focus on crime at the event are "unfair".

"I think there are definitely racial undertones. It's not white people portrayed in these crimes. It is black gangs portrayed, and of course the carnival is next to many million-pound houses who would love to see us get out of town and go to a park."

'I won't wear something expensive'

Jo Jordan, 23, was attacked by a gang who stabbed him in the arm and stole his watch at the carnival last August.

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Media captionJo Jordan says the number of people enjoying carnival outweighs those making trouble

Despite his injury, he believes the number of arrests at carnival represents "the small minority who go for the wrong reasons".

"It's a scary world we live in - I could be walking down the street and someone could try and rob me so you need to be careful. If I'm going to go [this year] I won't wear something expensive and attract attention.

"But there's still so much positive thing to gain from carnival, I feel like something needs to be done to stop the bad outweighing the good."

10,000 narratives

Lucy Knight, 46, from Shepherd's Bush, has been been to every carnival since she was 13.

"I can't say carnival doesn't have a problem because that would be to ignore the fact that when you have a million people in one area you're going to have crime rates and when you have people drinking and got people doing drugs there is going to be crime.

"But you have to look at the statistics when held against other festivals and events. If you look at any town on a Saturday night and you will find more crime there than carnival statistically speaking."

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About a million people attended last year's carnival

The carnival's organiser, London Notting Hill Carnival Enterprises Trust, says its focus is on "our community, our culture and having a celebration".

Trustee Kemi Sobers said: "There is this relentlessness on crime which we find is deeply unfortunate. If there was no crime in the wider society and there was crime at carnival then perhaps we focus on that.

"We do our utmost to ensure the safety and security of the million people that come to our event and try to stress policing yourself.

"We have 1,000 stewards there to help us and as back-up we have the Met Police as part of a range of emergency services that support our event.

"There are 10,000 narratives that you could extrapolate from carnival and its preparation this week. Some choose to concentrate on policing and crime and we choose to concentrate on our community."